The UNIX.RTM. System was designed in the 1970's as a general purpose, multiuser, interactive operating system for minicomputers. The communications environment in UNIX is designed around a simple character input/output interface mechanism. This mechanism, which processes one character at a time, is thus unable to effectively support a broad range of devices, speeds, modes and protocols, such as the current generation of networking protocols exemplified by Systems Network Architecture (SNA), Transmission Control Protocol/Internet Protocol (TCP/IP) and Xerox Network Systems (XNS). Such protocols provide significant functionality and features but cannot be efficiently integrated for use with the UNIX operating system due the lack of a standard interface.
There have been attempts to solve this problem through the development of special tools such as AT&T's STREAMS, which is a collection of system calls, kernel resources and kernel utility routines that define standard interfaces for character input/output within the UNIX kernel, and between the kernel and the rest of the UNIX System. The STREAMS mechanism is described in the UNIX System V/386 Release 3.2 Streams Primer (1989). The Berkeley Standard Distribution ("BSD") form of the UNIX kernel has a similar mechanism commonly referred to Berkeley Sockets.
Conceptually, AT&T's STREAMS and Berkeley Sockets support development of interface standards for character input/output within the UNIX kernel, and between the kernel and the user level. Unfortunately, these tools have not been effectively developed to the extent necessary to enable the UNIX operating system to be interconnected and integrated with existing diverse networks. The many desirable features and characteristics of the UNIX System therefore have not been available to users of PC's and local area networks because of this connectivity problem.
It would therefore be desirable to provide a method of integrating a multiuser, interactive operating system such as UNIX with other computing systems, networks, applications and information.